This invention concerns aqueous urea utilized as fire controlling agent. The invention also concerns the preparation and use of aqueous urea. The aqueous urea is useful to stop house fires, grass and forest fires, to produce flame retarded water based plastic, flame retarded polyurethane foam, etc, and flame retard flammable organic materials by spraying the outside with aqueous urea and/or an aqueous urea composition.
Urea in the form of a solid compound has been used as a flame retardant agent in polyurethane foams as outline in U.S. Pat. No. 4,385,131 (racalossi et al.). Many patents use solid urea condensates, urea phosphates, urea borates and urea derivative as the flame retardant agent. The use of aqueous urea as the flame retardant compound is novel. When solid urea is used in sufficient amounts, as the flame retardant retardant compound in the production flame retardant organic products, such as polyurethane products it leaves a slimy or soapy feel to the outer surface of the urethane products, which is very undesirable. The urea migrates out and the product becomes less fire retardant. When the aqueous urea is utilized, the water and urea reacts with the polyisocyanate and becomes a part of the product. There is no slimy or soapy feel to this foam. Aqueous urea is a fertilizer and is very environmentally safe product to use on grass and forest fires. When used for fire fighting the aqueous urea may contain coloring agents such as iron oxide, thickening agents, gellng agents, corrosive inhibitors, bactericide agents, surfactant and wetting agents. Aqueous urea is more economical to use to fight fires than the commonly used fire fighting chemicals such as various ammonium phosphates, and ammonium sulfate.
What is lacking and what is needed are useful, safe and inexpensive flame retardant compounds found in aqueous urea. What is additionally lacking are compositions have aqueous urea employed therein.
In one aspect, the invention comprises the flame retardant aqueous urea. Another aspect of the invention is a process to prepare the aqueous urea by producing the urea from ammonia and carbon dioxide in an aqueous solution. Urea is commercially available.
Another aspect of this invention is the process to prepare an aqueous urea composition by mixing:
(A) aqueous urea, in the amount of 25 to 200 parts by weight;
(B) carbonization auxiliaries, in the amount of 0 to 200 parts by weight;
(C) metal containing compound that will accelerate the carbonization process, in the amount of 0 to 30 parts by weight;
(D) heat reflecting compound, in the amount of 0 to 30 parts by weight;
(E) filler, in the amount of 0 to 200 parts by weight;
(F) surfactant, in the amount of 0 to 30 parts by weight.
Another aspect of this invention is to apply on and/or incorporating in a more flammable organic material (Component G) the flame retardant compounds, aqueous urea and/or the aqueous urea composition.
Another aspect of this invention is to utilize the aqueous urea and/or the aqueous urea composition to fight fires such as grass fires, forest fires, house fires, furniture fires, etc. In fighting grass fires a water diluted solution of aqueous urea and/or aqueous urea composition with or without surfactant, to produce bubbles may be sprayed directly on the flames or may be sprayed in front of the flames thereby wetting the organic materials in front of the fire. The aqueous urea and/or aqueous urea composition, even after drying, and for several day afterwards, will prevent the coated organic materials such as grass, leaves and bushes from catching on fire when exposed to flames.
Any suitable aqueous urea may be utilized in this invention. The aqueous urea produced in the manufacturing process of producing urea and/or the aqueous urea produced by adding solid urea to water. Usually the aqueous solution of urea contains 50% or less of urea.
Any suitable carbonization auxiliaries may be utilized in this invention. Suitable carbonization auxiliaries are compounds that in the presence of fire assist the formation of a carbonization foam or char, such as, additives that produce acidic components in the pyrolysis mixture, such as phosphorus acids, boric acids or sulfuric acids. These acidic components are compounds such, for example, acids or salts, or their derivatives of sulfur, boron and phosphorus, such as, boron-phosphates, phosphates, and polyphosphates of ammonia, amines, polyamines, amino compounds, thioureas and alkyanolamines, but boric acid and its salts and their derivatives, organic phosphorus compounds and their salts, halogenated organic phosphorus compounds, their salts and their derivatives, sulfuric acids, their salts and their derivatives such as ammonium sulfate, urea sulfate, etc., may also be used for this purpose. The commonly known fertilizer which contains phosphorus or sulfur are inexpensive carbonization auxiliaries that can be used with the aqueous urea especially in fire fighting and fire prevention and are preferred. The carbonization auxiliaries and other flame retardant agents may be used in quantities of 0 to 200 parts by weight. The carbonization auxiliaries and other flame retardant agents are not a necessary component but when used is used in an amount of 5 to 200 part by weight.
The nitrogen containing salts of phosphorus acids are the preferred carbonization compounds, such as amino phosphate, amine and polyamine phosphates, amino salts of organic phosphorus compounds and amino condensation salt of inorganic and organic phosphorus compounds. The condensation salt of phosphorus compounds are produced by contacting urea condensates such as, biuret, cyanuric acid and cyamelide or other amino compounds with a phosphorus containing compound that will react with an amino compound, under conditions sufficient to prepare an amino salts of a phosphorus containing compound. Suitable inorganic phosphorus compounds include, but not limited to, phosphoric acid, pyrophosphoric add, triphosphoric acid, metaphosphoric acid, phosphorous acid, hydrophosphorous acid, phosphinic acid, phosphinous acid, phosphine oxide, phosphorus trihalides, phosphorus oxyhalides, phosphorus oxide, and their salts, amino phosphates, amine phosphates, mono-metal hydrogen phosphates, ammonium dihydrogen phosphate, ammonium phosphate, bromated phosphates, alkali metal dihydrogen phosphate, and halogenated phosphate-phosphite and their halides and acids. organic phosphorus compounds include, but not limited to, alkyl, cyclic, aryl and alkyl-aryl phosphorus compounds, such as, alkylchlorophosphines, alkyl phosphines, alkyl phosphites, dialkyl hydrogen phosphites, dialkyl alkyl phosphonates, trialkyl phosphites, organic acid phosphates, organic diphosphonate esters, aryl phosphites, aryl hydrogen phosphates, halogenated phosphonates esters, biuret phosphate, cyanuric phosphate, cyamelide phosphate, and urea, biuret, cyanuric acid and cyamelide borates and mixtures thereof.
Any suitable metal-containing compound that will accelerate carbonization effect used in this invention increases the amount of carbonization residue after combustion, thereby enhancing the flame retardant effect and may be used in this invention. These compounds include, but not limited to, alkaline earth metal borates such as magnesium borate, calcium magnesium borate and the like, manganese borate, zinc borate, metal oxides of titanium oxide, tin oxide, nickel oxide, zinc oxide and the like, ferrocene, dimethylglyoxime copper, acetyl-acetonatocooper, hydroxyquinoline nickel and the like, zinc thiocarbamate compounds such as zinc dimethylthio-carbamate , zinc di-n-butyidithiocarbamate and the like, mercaptobenzothiazole zinc compounds such as mercaptobenzothiazole zinc and the like, salicyadehyde zinc compounds such as salicylaldehyde zinc and the like, metal hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium magnesium hydroxide, zirconium hydroxide and the like and mixtures thereof. The most preferable compounds are selected from zinc oxide, zinc thiocarbamates, the mercaptobenzothiazole zinc compounds the salicyaldehyde zinc compounds, zinc borate and the alkaline earth metal borates. The are utilized in the amount of 0 to 30 parts by weight. These metal containing carbonization accelerators are not necessary components but when used it is used in the amount of 1 to 30 parts by weight.
Any suitable compound that will reflect heat compound such as titanium oxide may be used in this invention and used in the amount of 0 to 30 part by weight.
Any suitable filler may be used in this invention. The fillers that may be utilized in the flame retardant mixture are usually insoluble in the reaction mixtures. They may be inorganic substances, such as, alkali metal silicates, alkaline earth metal silicates, metal silicates, silica, metals, oxides, carbonates, sulphates, phosphates, borates, glass beads or hollow glass beads. Hydrated aluminum oxide is preferred. They may be organic substances, such as, amino compounds, such as urea, melamine, dicyandiamide, urea condensates, urea-amino condensates, partially hydrolyzed urea condensates and other amino derivatives or their formaldehyde resins, amino phosphates, amino salts of organic phosphates, phenol-aldehyde resin powder, ammonium sulfates, urea sulfates, nitrogen containing sulfates, powdered coke, graphite, graphite compounds, Portland cement and mixtures thereof. The organic halide flame retardant compounds may also be added as fillers. The filler may be used in the amount of 0 to 200 weight of the partially hydrolyzed amino condensation compound. Fillers are not a necessary component, but useful, and if used is used in the amount of 1 to 200 parts by weight.
Any suitable surfactant that will assist in the production of bubbles or used as a wetting agent may be used in this invention, such as soaps, detergents and silicon surfactants, such as water-soluble polyester siloxanes. Any surface active agent that will assist in the formation of foam or as a wetting agent such as cationic, anionic, non-ionic and amphoteric surfactants may be used in this invention. The surfactant may be used in the amount of 0 to 30 parts by weight. The surfactant is not a necessary component except when bubbles and wetting agents are desired, then it is used in the amount of 1 to 30 parts by weight.
Any suitable organic material which is more flammable than the aqueous urea and/or the aqueous urea composition may be used in this invention. Any suitable plastic resin composition or mixtures thereof and any suitable natural organic material maybe used in this invention and mixtures thereof. These materials may be in the form of a solid, cellular suspension, emulsion or solution but the plastic are preferable to be in the form of or a suspension, emulsion , solution or as a liquid monomer. Suitable plastic resin include, but not limited to, vinyl dienes, vinyl-diene copolymers, polyesters, polyester resins, phenoplasts, aminoplasts, polyepoxy resins, polyurethanes, furans, polyamides, polyimides, polycarbonates, homopolymers of such olefins as ethylene, propylene, and butylene; block copolymers, consisting of optional combination of these olefins; polymers of vinyl compounds such as vinyl chloride, acrylonitrile, methyl acrylates, vinyl acetates and styrene; copolymers of the foregoing olefins with vinyl monomers, copolymers and terpolymers of the foregoing olefins, with diene compounds; polyesters such as polyethylene terephthalate, polyester resins; polyamides such as nylon; polycarbonates, polyoxymethylene, silicones, polyethers, thioplasts, polytetrafluoroethylene, polysulfones, vinyidienes, poly(vinyl acet compounds, cyclic unsaturated compounds, urethane-epoxy resins, polyimides, urethane silicates, cellulose nitrate rayon, regenerated cellulose film cellulose acetate, cellulose esters, cellulose ethers, cyanoethyl cellulose, chlorinated rubber and mixtures thereof.
Suitable natural products include but not limited to grass, weeds, leaves, wood, cellulose, lignincellulose, paper, cotton, wool, linen, dammars, copols, other natural resins, rosins, lignin, natural rubber, natural proteins, e.g., soya bean protein, silk, glues, gelatin, etc.; modified cellulose and mixtures thereof. Natural organic material and plastics may be mixed together. The aqueous urea and/or the aqueous urea composition, maybe utilized in the amount of 3-200 percent, percentage based on the weight of the more flammable organic material.
Any suitable polyisocyanate may be used in this invention organic polyisocyanates are preferred. The commercial available ones are preferred such as tolylene-2,4-dilsocyanate, tolylene-2,6-diisocyanate, polymethylene polyphenyl isocyanate, diphenylmethane 4,4xe2x80x2-diisocyanate, 3-methlydiphenyl-methane-4,4xe2x80x2-diisocyanate, m- and p-phenylenediisocyanante, polyphenylpolymethylene isocyanates obtained by phosgenation, commercially known as xe2x80x9ccrude MDIxe2x80x9d, modified polyisacyanates and mixtures thereof . Suitable organic polyisocyanates are exemplified by the organic diisocyanate which are compounds of the general formula
Oxe2x95x90Cxe2x95x90Nxe2x80x94Rxe2x80x94Nxe2x80x94Cxe2x95x90O
wherein R is a divalent organic radical such as an alkylene, aralkylene or arylene radical. Such radical may contain 2 to 20 carbon atoms. Any suitable compound with active hydrogens may be reacted with the polyisocyanates to produce polyurethane products. The preferred compound with active hydrogens are polyols. Polyurethane catalyst, blowing agents, surfactants, foam stabilizers, dyestuff, plasticizers, propellant, desiccant and fillers may also be used. Polyisocyanate which has the formula
Q(NCO)m
in which m represent a number from 2 to 4 and Q represents an aliphatic hydrocarbon radical having 2 to 18 C atoms, a cycloaliphatic hydrocarbon radical having 4 to 15 C atoms, an aromatic hydrocarbon radical having 6 to 15 C atoms, or araliphatic hydrocarbon radical having 8 to 15 C atoms and an organic compounds with 1 or more active hydrogens which will react with an isocyanate, in the amount of 25 to 100 parts by weight, containing a urethane catalyst, in the amount of 0.25 to 10 parts by weight, a plasticizer, propellants and a silicone surfactant, in the amount of 0.5 to 5 parts by weight, may be used as the flammable organic material. Any suitable polyepoxy compounds may be used in this invention such as ally glycidyl ether, tert-butyl glycidyl, and the like.
In general, the aqueous urea usually produced by reacting ammonia and carbon dioxide in an aqueous medium while under heat and pressure. This aqueous urea may be utilized in this invention or the urea can be crystalized by removing some of the water. The solid urea may then be added to water to form an aqueous solution of urea which usually contains less than 50% urea. The aqueous urea may be heated to about its boiling point to produce urea condensates which are soluble in water.
Any amount of the aqueous urea and/or aqueous urea composition, which may include carbonization auxiliaries, metal containing compounds that accelerated carbonization, heat reflecting substances, surfactant and fillers. Preferably, when the aqueous urea and/or aqueous urea composition is incorporated in the more flammable organic material an amount of 3 to 200% by weight, percentage based on the weight of the more flammable organic material is utilized. When the aqueous urea and/or aqueous urea composition is applied on the more flammable organic material a sufficient amount that will produce a less flammable organic material is utilized. Usually an amount that will wet the surface of the flammable organic material is sufficient.
The aqueous urea and/or aqueous urea condensate and/or aqueous urea composition is usually added on or incorporated in the flammable organic material at ambient temperature and pressure but elevated temperatures and pressure may be utilized when necessary.
One method to measure this flame retardant capability is an oxygen index test. By selecting the various combinations of the mixture of aqueous urea compositions to incorporate into a more flammable organic material the average limiting oxygen index (LOI) can be raised 10 to 30 percent or more when compared to otherwise comparable samples without the flame retardant aqueous urea composition. For example the LOI of three flexible polyurethane foams with the aqueous urea composition were raised more than 30 percent to a LOI of 31.7, 30.3 and 30.7.
When the aqueous urea and/or aqueous urea composition was incorporated into rigid polyurethane foam and tested with a propane torch with a 2xe2x80x3 flame held against the foam for one minute, the flame did not spread, the foam melted and/or a char was formed. The flame went out when the torch was removed.
Various aqueous urea compositions were incorporated into liquid resins then cured into a solid in the form of a xe2x85x9xe2x80x3xc3x972xe2x80x3xc3x976xe2x80x3 sample, for example, flexible polyepoxy resins, rigid polyepoxy resins, polyester laminating and flexible resin, polystyrene resin, polymethyl methyl acrylate resin, polyvinyl acetate resin, polyurethane, polyisoprene, polyethylene, acrylonitrile, etc, then tested with a propane torch having a 2xe2x80x3 flame, and held against the sample for one minute, the flame did not spread, and went out when the flame was removed. Various mixture of aqueous urea and/or aqueous urea compositions was add to aqueous emulsions and organic solutions of the above plastics then dried to form a test sample, then tested as above.
The flexible flame retardant polyurethane foams were tested and passed the Calif. TB 133 test which utilizes a 100 gms of wood in the form of a crib being burned on top of the flexible foam. If more than 60 gms of the foam bums away it fails this test.
Various natural products such as wood shingles, paper, cotton cloth, and cardboard were coated with various aqueous urea compositions in an aqueous emulsion containing 30% by weight of the aqueous urea composition with or without adhesives, then after the product had dried, they were tested by applying a 2xe2x80x3 flame from a propane torch against the products, and the flame did not spread whereas the non coated products caught on fire and burned.